1. Field of the Invention
The present invention relates to a lacquer bullet gun gas entry valve, particularly to a lacquer bullet gun gas entry valve providing controlled entry of compressed gas.
2. Description of Related Art
As shown in FIG. 5, a conventional lacquer bullet gun mainly comprises: a gun case 1; a barrel 2 at a front end of the gun case 1; a bullet chamber 3 at a rear end of the barrel 2; a feeding hole 4 above the bullet chamber 3, feeding one lacquer bullet 5 at a time into the bullet chamber 3, which are subsequently driven out through the barrel 2 by compressed gas; a firing device 6 inside the gun case 1, performing rearward and forward movements, while moving forward pushing the lacquer bullet 5 into the bullet chamber 3 to be fired; a gas container 8, supplying compressed gas through a pressure-reducing valve 9 into an expansion chamber 10, which is located below the bullet chamber 3 and connected thereto by a conduit 11; and a gas entry valve 12. The gas entry valve 12 further comprises: a valve body 13, a shutter 15, a spring 16 and a piston 17. The valve body 13 is placed in the expansion chamber 10 at an entrance of the conduit 11 and has a central axis, defining a longitudinal direction, along which a passageway 14 runs. An opening 141 is placed on an upper side of the passageway 14, being aligned with the conduit 11, so that the passageway 14 and the conduit 11 are connected. The shutter 15 is located on the central axis of the valve body 13, having a sealing element for sealing the shutter 15 against the valve body 13, preventing gas from entering the passageway 14 within the valve body 13. A rod 151 is attached to the shutter 15 and passes through the passageway 14 along the longitudinal direction, having a rear end that reaches out of a rear side of the valve body 13 opposite to the shutter 15. The spring 16 pushes the shutter 15 tight on the valve body 13. The piston 17 is connected to a lower part of the firing device 6, glidingly moving within the expansion chamber 10.
When the firing device 6 moves forward, the piston 17 moves along and pushes the rod 151 forward, causing the shutter 15 to separate from the valve body 13 and allowing compressed gas to enter the bullet chamber 3 through the passageway 14 in the valve body 13 to drive out the lacquer bullet 5 through the barrel 2. When the shutter 15 opens, pushed by the piston 17, gas partly enters a rear section of the expansion chamber 10 through a gap between the rod 151 and a rear end of the passageway 14, pushing the piston 17 rearward, so that the firing device 6 returns to a ready state, as before firing.
For controlling gas flow into the rear section of the expansion chamber 10 and pressure exerted there to prevent too large a pressure from pushing the piston 17 rearward too fast and, on the other hand, to create sufficient pressure to push the piston 17 rearward, the rear end of the rod 151 carries a blocking part 153. The blocking part 153 has several longitudinal grooves 154 and has a diameter that is equal to the diameter of the passageway 14. Thus gas from the passageway 14 is blocked from passing, except for the grooves 154. The number and widths of the grooves 154 determine the flow of gas into the rear section of the expansion chamber 10 and gas pressure there, controlling gas pressure on the piston 17.
The number and width of the grooves 154 needs to be adapted to the compressed gas pressure at which the lacquer bullet gun operates for the lacquer bullet gun to work regularly. However, various gases are used as driving agents which have various operating pressures. Nowadays, mainly carbon dioxide and nitrogen are used, with carbon dioxide having a larger operating pressure than nitrogen. Therefore, using nitrogen as a driving agent requires a larger number of grooves 154 at the rear end of the rod 151 at the shutter 15 to form a wider path for gas to flow into the rear section of the expansion chamber 10 to develop sufficient pressure on the piston 17. If, on the other hand, carbon dioxide is used as a driving agent, the number or widths of the grooves 154 has to be reduced, so as to reduce pressure on the piston 17 and preventing the piston 17 from moving back too fast.
Adapting the gas entry valve to various driving agents with various operating pressures requires different designs thereof. Especially, when carbon dioxide as a driving agent is replaced by nitrogen, pressure to push back the piston 17 is insufficient. When nitrogen as a driving agent is replaced by carbon dioxide, pressure to push back the piston 17 is too large, possibly resulting in breakdowns. Conventional lacquer bullet guns are thus restricted to one type of driving agents, which is rather inconvenient.
Since gas entry valves for two different driving agents cannot be exchanged, two types of gas entry valves for lacquer bullet guns have to be employed, increasing working effort and cost of production.
It is the main object of the present invention to provide a lacquer bullet gun gas entry valve, allowing to use various driving agents for the lacquer bullet gun without modification.
Another object of the present invention is to provide a lacquer bullet gun gas entry valve, allowing to use two agents for the lacquer bullet gun at the same time for better convenience.
The present invention can be more fully understood by reference to the following description and accompanying drawings.